Modern navigation devices, including smart phones and tablet PCs, implement a variety of navigation functionalities, such as route calculation between predetermined geographic positions, provision and visualization of digital maps, visualization of road networks and calculated routes, location and visualization of Point of Interests, or POIs, search functionalities for POIs, street names and location names, route guidance functionalities, provisioning of traffic information data, and so on. All these functionalities require large amounts of navigation information in digitized form that has to be appropriately organized and connected with each other. For this purpose, at least routing data representing a real road network along with associated attributes is organized in relational databases and stored onboard of the device (for instance, on an SD card). Other information associated with, for instance, traffic information may be also provided online.
Generally, routing data provided by map data suppliers comprises route link data and route node data. Route node data represents junctions of the road network and comprises pairs of longitude (long) and latitude (lat) coordinate data. Route node data further comprises junction attributes defining the type and shape of junctions or intersection as well as how route links joining a node have to be connected with each other. Thus, route node data mediates connections between adjacent links joining the node. Route link data, in turn, represents road segments between consecutive intersections. It comprises a plurality of road segment attribute information, like the road type, road shape, road classification, lane information, travel direction, predefined travel velocity, and so on.
The shape (i.e., course) of a road segment can be described by a sequence of shape points associated with the corresponding route link. Each shape point comprises longitude and latitude coordinates and represents the shape of a portion of the corresponding road segment. Distances between consecutive shape points may amount to several tenths of meters (for instance, 10 to 20 meters for winding road sections and approximately 40 meters for straight road portions). Adjacent shape points may be connected by shape lines to form a so called road geometry line in form of a polyline. Thus, each route link is associated with a sequence of shape points and shape lines in between.
It may happen that routing data are inaccurately or erroneously digitalized such that the digitized routing data does not correctly reflect the geographic position or course of corresponding road segments. Still further, the road network may be subjected to continuous changes. Such continuous changes may, for instance, comprise the straightening of winding road portions, the transformation of cross-like intersections into roundabouts, the relocation of roads or intersections, and so on. Such changes are usually taken into account by future database updates.
Deviations in the road network geometry between the digitalized map data and the real road network may cause problems during route guidance, in map displaying and map matching (map matching defines a technique in which a currently measured geographic position (e.g., GPS or Galileo position) is adjusted with the geographic position of a visualized map on the navigation device screen). For instance, when travelling along a pre-calculated route comprising a street being inaccurately digitized, it may occur that during route guidance the navigation device erroneously assigns a measured user position to another street which deviates from the pre-calculated route. In such a case the routing algorithm may perform a re-routing and, as a consequence, maneuver instructions may be generated and outputted that are not compatible with the course of the pre-calculated route the user is currently following.
Currently, such annoying situations cannot be immediately remedied. The user has no possibility to immediately fix erroneous digitalization of map data by himself. The user can only report digitalization problems to the map provider. The user has to then wait until the map data supplier releases a map data update. However, even in case a new update is released, there is no guarantee that the error has been properly corrected. As such, the user has to deal with wrong digitalization over a longer time period which is very inconvenient for him.
Nowadays, first approaches for overcoming digitalization problems are available. For instance, TomTom has recently introduced a technique called “map share”, in which a user is allowed to add, delete and modify POI data. In addition, “map share” allows a user to correct attributes associated with route links such as the correction of velocity limitations or the correction of street names or the change in the turning behavior. Such a correction can be performed by marking the concerned road on the display and by inputting corrections following a displayed menu structures. The corrected data are then sent to a provider which approves the correction and provides the approved corrections to other users. With “map share” the course (shape) of road networks is not correctable.